Lift truck



April 25, 1939. A. M. BARETT LIFT TRUCK 5 Sheets-Sheet l Original Filed Feb. 25, 1955 April 25, 1939- A. M. BARRETT LIFT TRUCK original Filed Feb'. 25, 1955 5 Sheets-Sheet 2 nmllm V lll mww -SYM l l -um W/ l l I.. LVM.;

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April 25, 1939 A. M. BARRETT LIFT TRUCK Original Filed Feb. 25, 1935 3 Sheets-Sheet 3 H .INI

Patented Apr. 25, 1939 PATENT OFFlCE LIFT TRUCK Arthur M. Barrett, Winnetka, Ill., assigner to Barrett-Cravens Company, Chicago, Ill., a corporation of Illinois Application February 25, 1935, Serial No. 8,029 Renewed February 7, 1936 32 Claims.

The present invention relates generally to lift trucks and is particularly concerned with the provision of a slide lift truck having new and improved means for raising the lifting frame and for hydraulically checking the descent of the lifting frame after positively acting mechanical holding means has been released.

The principal object of the present invention is the provision of simplified lifting mechanism of the direct pull type but which is so constructed and arranged as to provide, rst, a multi-lift truck and, second, a mechanism by which the lifting frame can be raised by actuation 0f the steering handle of the truck in practically any steering position. Another object of the present invention is the provision of means for holding the pull link in operative position with means associated with said holding means for releasing the link to allow the lifting frame to lower, and it is a further object of the present invention to provide positively acting holding means for maintaining the lifting frame in its raised position with releasable. means operated in conjunction with the means for releasing said link.

A further object of the present invention is the provision of positively acting mechanical means for holding the lifting, frame in its raised position in connection with hydraulic means for checking the descent of the lifting frame, with the positive mechanical means enclosed within the casing of the hydraulic check so as to be protected and more effectively lubricated thereby. A still further object of the present invention is the provision of slides, rather than links, connecting the supporting means, usually a main frame, and the lifting frame whereby relative movement therebetween will cause the lifting frame to raise or lower.

These and other objects of the present invention will be apparent to those skilled in the art after a consideration` of the following detailed description of the preferred embodiment, taken in conjunction with tne accompanying drawings illustrating said embodiment.

In the drawings: Figure l is a top plan view of a lift truck embodying the principles of the present invention;

Figure 2 is a side view of the truck shown in Figure l;

Figure 3 is an enlarged section, taken along the line 3-3 of Figure l., showing the details of the lifting mechanism;

Figure 4 is a section taken approximately along the line -II of Figure 3;

55 Figure 5 is an enlarged horizontal section through the hydraulic check and associated mechanism;

Figure 6 is a section taken approximately along the line 6-6 of Figure 5;

Figure '7 is a section taken through the piston structure along the line 'I-I of Figures 8 and l0;

Figure 8 is a rear view of the check piston;

Figure 9 is a section taken along the line 9-9 of Figure 8; and

Figure l0 is a View of the piston structure showing the check valve retaining washer in place on the piston.

Referring now more particularly to Figures l, 2- and 3, reference numeral I indicates a wheeled supporting means upon which the lifting frame 2, which is adapted to be raised and lowered, is supported. The wheeled supporting means includes a main supporting frame 3 including side bars lI and 5 connected at their forward ends to a transverse crosshead i? including a central section 'I in which front steering means 8 is journaled for steering movement about a generally vertical axis. The rear end of the wheeled supporting means, or the rear ends of the main frame side bars 4 and 5, are supported by rear wheels 9 journaled for rotation on an axle I0, and the front steering means' usually includes relatively closely spaced front wheels II which are journaled on an axle I2 carried in any suitable manner at the lower end of a king bolt 4lli journaled, as aforesaid, in the crosshead 6, the latter having a central tubular boss I5 for this purpose, as best shown in Figure 3. The upper end of the king bolt I4 has secured thereto a steering head I6, clamped thereto by a clamping bolt I'I and provided with a pair of apertured ears I8 which support a pivot bolt I9 by which a steering handle 20 is connected with the steering head I6. The handle 20 is utilized for pulling the truck from place to place and is also provided with latch means 2| which, when the steering handle 20 is swung to an upper position, engages suitable mechanism for raising the lifting frame 2, as will be pointed out in detail later.

So far as the front steering truck and steering handle and associated parts are concerned, the construction employed is quite similar to that shown in my Patent No. 1,803,688, issued May 5, 1931. However, in the present case, the pivot connection between the lifting handle and the steering handle is disposed somewhat farther forward than in the aforesaid patent. As in the aforesaid patent, the lift truck is provided with a lifting lever or horn 25 having a hooked upper end 26 which is adapted to be engaged by the handle-carried latch means 2| when it is desired to operate the lifting handle to raise the lifting frame. The lifting lever or horn 25 in.- cludes a curved section 28 and a forwardly extending section 29 terminating in a portion journaled for pivotal movement on the same pivot I9 upon which the lifting ha-ndle 20 itself is mounted. Thus, by engaging the latch 2| with the end 26 of the lifting lever 25, the latter may be swung about its axis I9 in a generally vertical plane by swinging the steering handle 20.

The lifting frame 2 consists principally of a U-shaped frame bar 35 which includes side bar sections 36 and 31 extending forwardly along the main frame 3 substantially to the front crosshead 6, as best shown in Figure 1. Each of the side bars 4 and 5 of the supporting frame 3 is provided with a pair of lower frame slides 39 and 40 rigidly secured thereto in a downwardly and rearwardly inclined position, as best shown in Figures 2 and 3, the slides 39 and 40 at each side of the main frame 3 being secured to the outer sides of the side bars 4 and 5, as best shown n Figure 1. The side bar sections 36 and 31 of the lifting frame 2 have secured thereto on the inner sides thereof companion slides 4|, 42 and 43. As best shown in Figures 2 and 3, the forward lower frame slides 39 receive the forward upper frame slides 4|, and at the rear of the truck the lower frame slides 40 are embraced by the pair of upper frame slides 42 and 43 at each side of the lifting frame. By virtue of this construction, whenever the lifting frame is shifted forwardly, or forwardly and upwardly, with respect to the wheeled supporting main frame, the lifting frame 2 will be raised upwardly from the position shown in full lines in Figure 2 to the position shown in dotted lines. From Figure 2 it will also be seen that the rear axle I6, supporting the rear wheels 9, is carried directly by the two lower frame slides 40. The forward ends of the side bar sections 36 and 31 of the lifting frame are preferably connected together by an angle member 45 having a horizontal section 46 and a vertical section 41, the member 45 serving as a platform stop and prevents any load supported on the lifting frame 2 from coming into contact with the lifting mechanism by which the lifting frame is raised through the operation of the steering handle 20.

The means for raising the lifting frame 2, by the operation of the steering handle 20 from any normal steering position, will now be described and, it will be noted, consists of suitable mechanism for exerting a. pull on the lifting frame substantially at the same angle with respect thereto as said upper and lower frame slides. Referring now more particularly to Figures 1 and 3, a pair of laterally spaced rearwardly eX- tending lugs 50 and 5| are formed on the crosshead 6 and are apertured to receive a pair of transversely disposed pivot shafts 53 and 54. A lifting arm 56 is mounted for rocking movement in a generally vertical longitudinal plane with respect to the wheeled supporting frame and includes an upwardly extending arm section 51 having a hook-like end 58 with a rounded section 59. The upwardly extending arm section 51 is carried by or forms. a part of a yoke section 60 which is provided with a pair of laterally spaced arms 6| and 62 having sleeve or bushing extensions 63 and 64 pivotally mounted on the forward pivot shaft 53, as best shown in Figure 1. The sections 6| and 62 are spaced apart, and

disposed therebetween is a torsion spring 61 having one end 68 bearing against the cross-head 6 and the other end 69 engaging the yoke section 68 so as to resiliently urge the lifting arm 56 for movement rearwardly toward the lifting fram-e 2.

The lifting arm 56 is operatively connected with the lifting lever or horn 25 by means of a double eye link 13 having rounded ends 14 and 15, the latter being disposed over the hook-like end 58 of the lifting arm 56 and received within the curved portion 59 thereof, and the end 14 of the link 13 being disposed over the upper portion of the lifting horn or lever 25 and received by the curved portion 28 of the latter. Thus, by engaging the latch mechanism 2| and rocking the handle 20, the lifting lever 25 may be rocked back and forth and will transmit through said link 13 similar rocking movement to the lifting arm 56.

The lifting arm 56 is operatively connected with the lifting frame so that the rocking movements of the arm will cause the lifting frame to be raised. To this end, a draft member in the form of a pull link 88 is formed with a bearing sleeve section 8| journaled for rocking movement on a pivot pin 82 carried by the lifting arm 56 a short distance above the axis of the pivot shaft 53 on which the lifting arm is pivotally mounted. The lower end of the pull link is threaded, as at 85, to adjustably receive a pawl member 86 which is provided with cooperating internal threads and a plurality of pawl teeth 81 facing upwardly and held in that position in any position of adjustment by means of a pin 88 carried in the lower end of the link 80 and disposed in a slot 89 formed in the lower part of the pawl member 86, as best shown in Figure 3. From the latter figure it will be observed that the link 80, being disposed substantially at the same angle as the slides 39 and 40, is subject to practically a direct pull in elevating the lifting frame.

Cooperating with the pawl member is a ratchet plate 95 rigidly and permanently secured to and carried by the front portion of the lifting frame 2, and the ratchet member 95 is provided with two downwardly disposed teeth 96 and 91, the latter being spaced rearwardly anddownwardly from the former a distance equal to a multiple of the spacing between adjacent teeth 81 on the pawl member 86, as best shown in dotted lines in Figure 3. The teeth 96 and 91 are disposed in a position to be successively engaged by the pawl member 86, that is, with the lifting frame in its lowered position, the first oscillations of the pull link will cause the pawl member to progressively engage the upper tooth means 96 until the lifting frame is about half raised, and then the pawl member will progressively engage the lower tooth 91 to complete the raising of the lifting frame. As a result of the above menytioned spacing between the teeth 96 and 91, neither the pawl 86 nor the ratchet plate 95 need be very long and hence will require only a small space at the truck head and can be inexpensive parts. but all o-f the advantages of a multi-lift truck are retained. For example, where the maximum spacing between the teeth 96 and 91 on the ratchet is such that at least the majority of the group of teeth on the lifting pawl fits in between the teeth 96 and 91,k the lifting frame can, if desired, be raised in a number of steps equal to approximately twice the number of teeth on the lifting pawl. It is to be understood, of course, that the number of teeth of the pawl and ratchet members 86 and 95 may vary as desired. In the preferred construction, the ratchet member 95 forms a part of a casting |30 which, as best shown in Figure 5, is provided with a pair of lateral lugs which may be bolted, as at |03, to the transverse angle or platform stop member 45. The casting or member |63, in addition, serves as a portion of the anchoring means for the hydraulic check which will be described later.

The draft or pull link 35 is heid up in its operating position, in which the ratchet mechanism Sii-95 is engaged and oscillations of the lifting arm 56 and the link 30 will raise the lifting frame, by suitable biased means acting against the shank portion of the link 89, and this means for holding the link in position also serves as a portion of the releasing means by which the ratchet mechanism is disengaged. The lifting pawl holding and releasing means comprises a member H best shown in Figure 1, which includes two arm sections I3 and journaled on the rearward pivot shaft 54, the laterally outer section H5 being disposed just outside the left hand shaft supporting lug 5| and the laterally inner portion H1 being disposed substantially underneath the arm portion 62 of the lifting lever 55, as best shown in Figure 1. The two sections HG and of the pawl release member H5 are joined together and terminate rearwardly in a laterally inwardly directed Contact lug |23 which is disposed alongside and contacts with the link 3G. To this end, the latter is preferably provided with a flattened section |2| slightly curved as indicated in Figure 3, and the under surface of this slide section |2| is adapted to be engaged by a roller |22 carried on a pin |23 supported by the member ||5 just underneath the contact lug |20, the roller being spaced below the latter a distance slightly in excess of the thickness of the fin or slide portion |25 of the link l8|). The member H5 is biased for movement in a counter-clockwise direction as viewed in Figure 3 by means of a spring |25 which has one end |26 bearing underneath the left hand supporting lug 5|, the other end |21 being disposed underneath the laterally inner arm section H1 of the pawl release member H5. By virtue of the bias of said spring, the roller |22 is caused to exert an upward force against the link 8B through the slide or iin section |2| thereof, whereby the link 8B and the pawl member 85 are held in their upper position with the latter in engagement with the ratchet plate 55.

The position of the pawl controlling member H5 is, in turn, governed by a treadle member |30 having sections |3| and |32 disposed generally at right angles with respect to each other and a pawl controlling projection |33 which is adapted to cooperate with a cam lug |34 carried by the pawl controlling member H5 on the arm section H5 thereof which is disposed laterally outwardly of the left hand shaft supporting lug 5|. This cam lug |34 includes a forwardly disposed nose |35 having a contact face adapted in the position shown to be engaged by the end of the projection |33, the latter in normal position being disposed within the recess or space between the forwardly extending nose |35 of the lug |34 and the journal portion of the arm H5 of the pawl release member H5. When the treadle |38 is depressed, as by the operator stepping on the same, the treadle arm |3| will be pressed downwardly until it engages the crosshead section, this serving to swing the projection |33 upwardly and causing the radially outer end thereof to act against the nose |35 and to cam the pawl release member in a clockwise direction about the pivot of the shaft 54. This, in turn, causes the contact lug |23 to bear against the slide portion |2| of the link 80 and to swing the latter downwardly so that the pawl 56 will move out of engagement with the ratchet plate 95 on the lifting frame 2. Depressing the treadle |3| down against the crosshead 6 also serves to move the end of the projection |33 upwardly and forwardly against the nose |35 of the lug |3i, as best shown in dotted lines in Figure 3, and in this position the spring |25, which normally tends to rotate the pawl release member |5 in a counterclockwise direction, is no longer effective and merely causes the nose of the lug |34 to bear against the projection |33, thus holding the pawl member 86 released from the ratchet plate 95. lli/'hen it is desired to restore operative relations fo-r the lifting pawl and ratchet mechanism, the operator steps on the other pedal |32, which rocks the member |30 in a clockwise direction and moves the projection |33 free of they nose |35 on the member H5, thus permitting the spring |25 to restore the latter to the position shown in full lines in Figure 3, so as to raise the link 80 and the pawl member 86 against the lifting frame and up into engagement with the ratchet 95. Thus, the pawl and ratchet mechanism 86--95 may be released and held in released position by merely stepping on the pedal |3|, and operative relations may be restored by stepping on the pedal |32.

Since the above described lifting mechanism for raising the lifting frame 2 includes ratchet mechanism having a plurality of teeth and therefore employs certain inherent features of a multilift truck, which is a type in which several oscillations of the lifting means are utilized for raising the lifting frame in a series of steps, means must be provided for temporarily holding the lifting frame in its intermediate positions while the lifting handle is swung to secure a new engagement of the ratchet mechanism. It is also desirable in lift trucks to provide some form of means for cushioning the descent of the lifting platform, especially when a load is supported thereon, so as to prevent racking and jarring the truck. According to the principles of the present invention, I embody both holding means and checking means in the same apparatus.

Referring now to Figures 3, 5 and 6, the reference numeral |46 indicates a casing having its rear end provided with a threaded abutment bushing Mi carried at the rear end of an interior cylindrical section |132. The bushing |4| is provided with a spherical seat |43 which receives the rounded head of a stud hid xed as by welding or the like in the central portion of a transverse angle member M5 bolted as by cap screws M5 to the side bars 4 and 5 of the main frame 3. The portion of the transverse member |55 receiving the rear end of the check casing |53 is in the form of an upstanding flange which includes laterally and forwardly angled portions 55| and |52 having their ends welded or otherwise secured to the end portions |53 of the member |45, as best shown in Figure 1. On either side of the stud |44, the rear end of the casing |40 carries rearwardly extending bolts |56, the ends of which extend rearwardly and are threaded to receive castellated nuts |51 against which springs |53 and |59 bear, the springs reacting against the rear side of the flange. The bolts |56 pass through enlarged openings in the flange, whereby lateral rocking movement of the casing |49 about the spherical abutment stud |44 is accommodated, but such rocking movement is resisted by the springs |58 and |59 which tend to hold the casing |40 in proper position. y

The cylindrical portion |42 extends from the rear wall forwardly to approximately the center of the casing |40, and the forward end of the cylindrical portion is connected with the side walls of the casing by a laterally transverse wall |60 formed integral with the walls of the casing |40 itself and the cylindrical portion |42. 'I'he forward wall of the casing |40 carries a central sleeve section |6| which extends rearwardly toward the cylindrical section |42, and the rear end of the sleeve section |6| is joined to the walls of the casing or integral wall or web section |63, as best shown in Figure 5. The portion of the casing forward of the transverse wall |66 and surrounding the sleeve section I5! forms a liquid reservoir |64 for a purpose which will be described later. The reservoir |64 is provided with a filler plug |65, and the forward portion of the casing |40, that is, that part forming the reservoir |64, is provided with walls such that the cross section thereof, as best shown in Figure 6, is rectangular, the upper wall of this portion of the casing being flat while the rear portion thereof has its upper walls curved as shown in said figure.

The cylindrical section |42 extends forwardly from the rear wall of the casing and the sleeve section |6| extends rearwardly from the front Wall of the casing in axial alignment and receive a long rod |66 the rear half of which is threaded, as at |61, and carries a piston |66 at its rear end securely fastened to the rod |66 by any suitable means. The forward half of the rod |66 is smooth and has its forwardmost end rounded and is received Within a spherical recess formed in the casting on which the ratchet teeth or ratchet plate 95 is carried.

The rod |66 is prevented from rotating in its spherical seat by means of a plate member |69 which is securely pinned or otherwise fixed to the forward end of the rod |66 and is provided with lateral sections |10 and i1| which are connected to the casting member |99 by bolts |12 the forward ends of which are threaded and receive nuts |13 between which and the rear flange of the casting |09 springs |14 and |15 are disposed and which function substantially the same as the springs |58 and |59 described above.

The forward end of the cylindrical portion |42 carries a thrust plate |16 which is provided with one or more bores |11 to accommodate flowI of liquid from the reservoir |64 into the cylinder |42. A ratchet wheel |18 is provided with internal threads corresponding to the threads |61 and is disposed between the rear end of the Vforward sleeve section |6| and the thrust plate |16. The ratchet wheel is thus held against axial movement, but rotation thereof is permitted upon the occurrence of relative movement between the casing |40 and the rod |66.

Cooperating with the ratchet wheel |13 is a pawl |19 journaled for rocking movement on a short shaft or cap screw |80, the forward end of which is secured in a boss |8| formed in the central casing web |63 and the rear end of which is threaded into a boss |82 formed on the rear of the transverse wall |60. The pawl |19 is provided With an arm 83 against which a spring |34, seated in a screw plug |85, bears. The spring |34 serves to rock the nose |19a of the pawl |19 against the teeth of the ratchet wheel |18.

By virtue of this construction, whenever the lifting frame is raised, sliding upwardly on the slides 4|, 42 and 43 carried by the lower or main supporting frame, the nonrotatable rod |66 is carried with it, being extended with respect to the casing |40 since the latter is anchored to the lower frame or main supporting means by the bolts |56. 'I'his relative movement of the rod |66 with respect to the casing causes the ratchet wheel |18 to rotate, in a counter-clockwise direction, as viewed in Figure 6, the nose |19a, of the pawl |18 riding over the ratchet teeth. However, the reverse movement of the rod |66 cannot take place, for when the rod is forced in the opposite direction, the ratchet wheel |18 also rotates in v the other direction until the pawl |19 engages one of the ratchet teeth. Thereafter, relative movement cannot occur, the ratchet wheel |18 and pawl |'i9 serving as positively acting mechanical means to prevent the lifting frame from lowering under its own weight or under the weight cf any load supported thereby. It is to be noted, also, that the ratchet wheel |18 is disposed within the reservoir i 64 and in contact with the Huid therein. This fluid is usually oil so that the operation of the ratchet mechanism |18|19 is both quiet and dependable, since the mechanism is enclosed and well lubricated at all times, and it is also free from dirt and dust and is in such a position that it cannot be injured easily, as by coming into violent contact with some object, which might occur where such ratchet holding means is exposed.

Since the ratchet mechanism |19-|19 just described operates at all times to permit extension of the rod |66 with respect to the casing |40 but at the same time serves to prevent retraction of the rod within the casing |40, means must be provided for disengaging the ratchet mechanism when it is actually desired to have the lifting frame lower. To this end, the left side wall of the casing |46 is provided with a boss |86 threaded at its outer end and apertured to receive a stub shaft |81 which is disposed within the hydraulic reservoir |64 and has secured thereto a pawlV release cam |88 bearing against the upper surface of the pawl arm |83. Suitable spring pressed packing means |99 prevents the escape of liquid from the reservoir |64 around the shaft |81, and the outer end of the latter from outside the casing Uit carries an operating arm |9| secured thereto by any suitable means |92, such as a set screw, key or pin (Figure 'Ihe lower or radially outer end of the arm |9| receives the rear laterally bent end |93 of a` control link |94 which extends forwardly and is connected, as at |95, with the ratchet release arm |96 which preferably is an integral part of the pedal member |30, whereby depression of the pedal |3| to drop they link 80 away from the ratchet plate 95 will, at the same time, exert a thrust on the link |94 to swing the arm ii in a counter-clockwise direction, thereby causing the cam |88 to depress the arm |63 on the pawl |19 and raise the latter out of engagement with the ratchet wheel |18. As will be apparent, disengagement of both the ratchet mechanism 96-95 and the ratchet mechanism HI8-|19 will permit the lifting frame to lower.

As the lifting frame lowers its downward movement is cushioned by the movement of the piston EES within the cylindrical section |42 of the casing |49. The piston |68 is best shown in Figures 8 and 9, and comprises an annular member 200 220 is provided, being anchored, as at 22|, to the having a diameter to closely fit the walls of the cylinder |42. The piston member 200 is provided With a keyway 20| adapted to receive a key 202 carried by the rear end of the piston rod |66, whereby the piston member 200 is prevented from turning on the rod |65. The piston member 200 is also provided with a notch 204 cut in the upper portion of the rear edge of the piston and cornmunicating with a vertical bore 205 which at its lower end leads into a transverse bore 20E near the lower portion of the member 200. The lower bore 206 communicates with a bleed opening 201 in the front face of the member 200 so that, with the valve means described below in its closed position, the load is allowed to gradually lower by the iiow of liquid from the rear side of the piston to the forward side thereof through the notch 25d, the bores 205 and 206, and the bleed opening 251. The purpose of disposing the notch 28d adjacent the upper edge of the piston is to provide for the dissipation of any air pockets on the back side of the piston. If air is allowed to be trapped at this point, repeated dropping of the load would occur when. the check is released, due to the compression of the air and leakage thereof. With the opening 205 at the top, the air passes over as the liquid from the back side of the piston is forced forward, and hence no air can remain on the pressure side of the piston for any length of time.

In order to provide for unrestrained raising of the load, the piston construction |68 is provided with check valve means indicated in its entirety by the reference numeral 2| 0 and including a ball 2|| seated in a bore 2I2 having a valve seat 2i3 to receive the ball 2| The larger end of the bore 2|2 communicates with the pressure side of the piston structure 68 so that when the descent of the load is checked the ball 2|| is forced tightly against its seat ZES, forcing all of the liquid to flow through the restricted opening 201, but when the load is raised and the piston moves outwardly of the cylinder, that is, to the left as viewed in Figure 5, the ball 2|| moves away from its seat and opens the passageway 2 I 2 for the free flow of liquid therethrough.

lThe ball 2|| is held in place by means of a plate or washer 2|5, best shown in Figures 'l and l0, comprising a ring member formed similarly to the piston member 200 and having an opening adapted to receive a pin 2|6 carried by the member. 205 on the back side thereof. The washer or plate 2|5 is provided with a lower opening 2|1 arranged slightly offset with respect to a vertical diameter, as best illustrated in Figure 10, By virtue of this construction, whether the washer 2|5 be applied in one position or in a reversed position, the hole 2|1 will be disposed sufficiently offset, on one side or the other, with respect to the bore 2|2 so that the ball 2|| cannot drop out or become dislodged, yet the opening 2|'l is large enough to provide for a free flow of liquid during the time that the load is raised and the piston structure |68 moves outwardly of the cylinder |42. The washer 2|5 is held in place by means of a nut 2|8 and, being tightly clamped by the latter, serves to close the rear end of the transverse bore 206 so that no liquid is lost at this point, but, during the cushioned descent of the load and at times when the valve ball 2|| is closed, all liquid is forced to flow through the restricted bleed opening 201.

In order that the lifting frame will lower even though no load is on the lifting frame, a spring rear transverse member |25, and at its forward end to the casting member |00, the latter having an opening 222 to receive the forward end of the spring 220.

The operation of the mechanism of the lift truck so far as it has been described above is substantially as follows: The truck may be pulled from place to place by the handle 20 and, when it is desired to raise a load, the lifting frame is moved to its lowered position (Figure 3) and backed or placed under the load. The latch 2| is then engaged with the upper hooked end of the lifting lever 25 and the handle 20 rocked back and forth in a generally vertical plane. Due to certain relations between the lifting lever 25 and the lifting arm 56, it is not necessary that the handle should be in a straight forward position, as will be explained later. oscillations of the lifting lever 25 about its pivot |9 operate through the link 13 to causethe lifting arm 56 to oscillate, and the oscillations of the latter reciprocate the link 80 and cause the tooth 96 on the ratchet member 95 to be engaged by successive teeth 81 on the pawl member 86 and then, in turn, the other tooth 91 on the ratchet member 95 is engaged by successive teeth on the pawl member 86 to raise the lifting platform in a series of steps. During the time between rre-engagement of the teeth the positively acting mechanical ratchet mechanism |18-I19, disposed within the check cylinder |40, acts to positively prevent the lifting frame from lowering from its intermediate position. When the load has been raised sufficiently, the latch 2| is disengaged and the truck may be pulled to another place by means of the handle 20.

When it is desired to lower the load, the operator steps on the pedal |3| to swing the pawl release member |5 downwardly, thereby releasing the link 80 and the pawl 86 from the lifting frame. At the same time the ratchet release arm |96 exerts a thrust on the link |94 to release the pawl |19 from the ratchet wheel |18, thereby releasing the aforesaid positively acting mechanical holding means and permitting the lifting frame with its load to lower under the control of the cushioning cylinder and piston construction |42-|68.

Referring now more particularly to Figure 3, it will be observed that normally the spring 61 serves to hold the lifting arm 56 in its rearward position, shown in full lines, and this disposes the forward end 14 ofthe link 13 and the curved portion of the horn 25 substantially in line with the steering axis of the lift truck, as defined by rthe king bolt I 4. Considering for the moment that the latch 2| is released and the handle 20 is swung downwardly to permit the truck being drawn from place to place, it will be apparent that this steering movement of the steering head I8 to steer the truck will have no effect upon the position of the link 13 although the steering horn 25 will be rotated about the vertical axis of the king boltrwithin the opening in the end 14. Now when the latch 2| is engaged by shiftingI the steering handle to its uppermost position, and then when the steering handle is swung downwardly to its forward or downward position, the lifting lever or horn 25 exerts a pull on the link 13 which swings the lifting arm 55 forwardly to the position shown in dotted lines in Figure 3. The parts are so designed that this extent of movement will swing the hook end 58 of the lifting arm 56 forwardly sol that the rounded portion 59 thereof now occupies the same position occupied formerly by the rounded portion 28 of the lifting horn 25, namely, in line with the Vsteering axis of the king bolt. By virtue of this arrangement, the steering handle 20 may be in practically any steering position and yet the same downward swing of the steering handle will cause the lifting arm 56 to be swung forwardly to the position shown in dotted lines in Figure 3, irrespective of the horizontal angular position of the steering handle. While in any position other than a straightforward one, the operation of the lifting lever 25 exerts some side thrust on the lifting arm 56, the relatively wide bearing which the latter has on the pivot shaft 53 effectively takes the reaction of any lateral component thereof, so that the lifting arm 56 will be swung forwardly to the same position at each time the lifting lever 25 is operated, whether straight forward or angularly with respect to the longitudinal center line of the truck.

While I have described above the preferred structure in which the principles of the present invention have been embodied, it is to be understood that my invention is not to be limited to the details shown and described, but that, in fact, widely different means may be employed in the practice of the broader aspects of my invention.

What I claim, therefore, and desire to secure by Letters Patent is:

l. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, means for raising said frame including a lifting arm movably mounted on said supporting means, a link operatively connected with said'arm, pawl and ratchet mechanism carried by said link and said lifting frame, and a spring pressed member operatively holding said link up in position with said ratchet means in engagement, whereby oscillations of said lifting arm serve to raise said frame, and means for rocking said spring pressed member away from said link to permit the latter to fall away from said lifting frame and thereby disengage said ratchet mechamsm.

2. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, means for raising said frame including a lifting arm movably mounted on said supporting means, a link operatively connected with said arm, cooperating ratchet mechanism carried by said link and said lifting frame, a member pivotally mounted on said wheeled supporting means and biased for movement upwardly into engage.

ment with said link for maintaining said ratchet mechanism in engagement, whereby oscillations of said lifting arm, acting through said link, will raise said frame, and pedal actuated means for swinging said spring pressed member against its bias for releasing said ratchet mechanism.

3. A lift truck comprising wheeled supporting means including front steering means movable about a generally vertical axis, a lifting lever pivotally connected with said wheeled supporting means forward of said axis, -a lifting frame movably connected with said supporting means and adapted to be raised and lowered with respect thereto, means for raising said frame including a lifting arm pivotally mounted on said wheeled supporting means rearwardly of said axis, a ratchet member xedly secured to said lifting frame, a pull link connected with said lifting arm and carrying a pawl cooperating with said ratchet member, and a link member connecting said lifting arm with said lifting lever and extending across the axis of said front steering means, whereby operation of said lifting lever swings said lifting arm and actuates said ratchet mechanism, and means for cushioning the descent of the lifting frame connected between said lifting frame and said Wheeled supporting means.

4. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, means for raising said frame including a lifting arm pivotally connected with said supporting means and a pull link pivoted to said arm and having ratchet connection with the lifting frame, means movably mounted on said supporting means and having a sliding connection with said link to accommodate reciprocation thereof and adapted to be operated to move said link out of engagement with said lifting frame to permit the latter to lower, and means connected between the lifting frame and said wheeled supporting means for cushioning the descent of the latter when said link has been disengaged.

5. A lift truck comprising wheeled supporting means having front steering means movable about a generally vertical axis, a lifting frame movably connected therewith, and means for raising said frame including a lifting arm pivotally mounted on said wheeled supporting means and constrained to move in a plane from a lowered position to a raised position in which a portion of the lifting arm is disposed substantially in line with said steering axis, means operatively connecting said lifting arm with said frame for raising the same, and means movable with said steering means about said axis and operatively connected with said portion of the lifting arm for actuating the latter.

6. A lift truck comprising wheeled supporting means including front steering means swingable about a generally vertical axis, a lifting frame movably connected with said wheeled supporting means to be raised and lowered with respect thereto, and means for raising said frame in-V cluding a lifting arm pivotally mounted on said wheeled supporting means about a transverse axis for fore and aft swinging movement in a vertical plane, means including a link operatively connecting said arm with said frame for raising the same, said arm having a hook-like end adapted in the forward position of the lifting arm to occupy a position in line with said axis, means for swinging said arm comprising a lifting lever pivotally mounted for swinging movement in a vertical plane which includes said axis, said lifting lever being movable with said steering means, and a link connecting said lifting lever with said hook-like end of said lifting arm.

7. A lift truck comprising wheeled supporting means including a steering head movable about a generally vertical axis, a lifting frame movably connected with said wheeled supporting means and adapted to be raised and lowered with respect thereto, and means for raising said frame including a lifting arm pivotally mounted on said wheeled supporting means for swinging movement in a generally fore and aft direction from a position in rear of said axis to a position substantially in line with said axis, means connected between said lifting arm and said lifting frame for raising the latter, a lifting lever pivotally connected with said steering head and movable from 8.- A lift'truck comprising wheeled supporting means, a lifting frame movably connected therewith, and means for raising said frame including a lifting arm movably mounted on said supporting means, a link operatively connected with said arm, a ratchet plate securely fixed to said lifting frame, a pawl carried at the end of said link and adapted to cooperate with said ratchet plate, and means providing for the adjustment of said pawl on said link relative to said lifting arm and said lifting frame.

9. A liftl truck comprising Wheeled supporting means, .a lifting frame movably connected therewith, means for raising said frame including a lifting arm movably mounted on said supporting means, a reciprocable link operatively connected with said arm and carrying a pawl at its lower end, a member carried by said lifting frame and having downwardly directed toothed means adapted to be engaged by said pawl, biased means movably carried by said supporting means and adapted to exert a continuous bias tending to hold said pawl up in engagement with said toothed member while accommodating the reciprocations of said link, and means separate from said biased means for moving the latter against its bias to hold said pawl away from said toothed member to permit the lifting frame to lower.

10. A lift truck comprising wheeled supporting means having a crosshead, front steering means journaled in said crosshead for movement about a generally vertical axis, a pair of laterally spaced rearwardly extending lugs carried by said crosshead, a lifting frame movably connected. with said wheeled supporting means and adapted to be raised and lowered with respect thereto, a shaft carried by said lugs, a lifting arm having laterally directed sleeve sections mounted for rocking movement on said shaft in a generally vertical plane, means connecting said lifting .arm with said lifting frame for raising the latter, and means carried by said steering head and connected with said lifting arm for actuating the latter to raise said lifting frame, said lifting arm having a portion adapted to be swung forwardly into line with the steering axis of said steering head.

ll. A lift truck comprising wheeled supporting means having a crosshead, front steering means journaled in said crosshead for movement about a generally vertical axis, a pair of laterally spaced rearwardly extending lugs carrie-d by said crosshead, a lifting frame movably connected with said wheeled supporting means and adapted to be raised and lowered with respect thereto, a shaft carried b y said lugs, a lifting arm having laterally directed sleeve sections mounted for rocking movement on said shaft in a generally vertical plane, means connecting said lifting arm with said lifting frame for raising the latter, means carried by said steering head and connected with said lifting arm for actuating the latter to raise said lifting frame, said lifting arm having a portion adapted to be swung forwardly into line with the steering axis of said steering head, and spring means encircling said shaft and disposed between said sleeve portions of said lifting arm for biasing the latter for movement in a direction toward said lifting frame.

12. A lift truck comprising wheeled supporting means having a crosshead, front steering means journaled in said crosshead for movement about a generally vertical axis, a pair of laterally spaced rearwardly extending lugs carried by said crosshead, a lifting frame movably connected with said Wheeled supporting means and adapted to be raised and lowered with respect thereto, a shaft carried by sai-d lugs, a lifting arm having laterally directed sleeve sections mounted for rocking movement on said shaft in a generally vertical plane, a link pivotally connected with said lifting arm and extending rearwardly, ratchet mechanism disposed between said link and said lifting frame and operable to raise the latter when said lifting arm is rocked fore and aft to reciprocate said link, a second shaft carried by said crosshead lugs, and means mounted on said second shaft and biasing said link for movement in one direction.

13. A lift truck comprising wheeled supporting means including a crosshead at the forward end thereof, front steering means journaled for movement in said crosshead about a generally vertical steering axis, a pair of laterally spaced lugs carried by said crosshead, a shaft carried by said lugs, a lifting arm journaled for movement in a generally fore and aft vertical plane, connecting means between said lifting arm and said lifting frame for raising the latter, spring means carried by said shaft and biasing said lifting arm for rearward movement, a second shaft carried by said lugs, said connections between the lifting arm and said lifting frame including a link pivotally connected at its forward end to said lifting arm and carrying at its rear end a pawl, a ratchet plate, means for hol-ding said pawl up into engagement with said ratchet plate comprising a member pivotally mounted on said second shaft and including a portion disposed laterally outwardly of one of sai-d lugs and another portion disposed adjacent said link, means carried by said member and engaging said link for controlling the position of the latter, and pedal means mounted on said first shaft and having a portion engageable with the portion of said member laterally outwardly of said one lug for controlling the position of said member and said link.

14. A lift truck comprising wheeled supporting means including a crosshead at the forward end thereof, front steering means journaled for movement in said crosshead about a generally vertical steering axis, a pairl of laterally spaced lugs carried by said crosshead, a shaft carried by said lugs, a lifting arm journaled for movement in a generally fore and aft vertical plane, connecting means between said lifting arm and said lifting frame for raising the latter, spring means carried bysaid shaft and biasing said lifting arm for rearward movement, a second shaft carried by said lugs, said connections between the lifting arm and said lifting frame including a link pivotally connected at its forward end to said lifting arm and carrying at its rear end a pawl, a ratchet plate, means for holding said pawl up into engagement with said ratchet plate comprising a member pivotally mounted on said second shaft and including a portion disposed laterally outwardly of one of said lugs and another portion disposed adjacent said link, means carried by said member and engaging said link for controlling the position of the latter, and pedal means mounted on said first shaft and having a portion engageable with the portion of said member laterally outwardly of said one lug for controlling the position of said member and said link, said pedal means being adapted when moved a certain extent for swinging said releasing member to shift said pawl out of engagement with said ratchet plate and adapted when moved an .additional amount to lock said releasing member in released position to permit said lifting frame to lower.

15..A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, means for raising said frame, hydraulic means for checking the descent of said frame and including a liquid tight casing, and releasable means-independent of said hydraulic checking means and including positively acting latch means disposed within said casing and serving when engaged to positively hold said lifting frame against descent.

16. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, means for raising and lowering said frame relative to said wheeled supporting means, and means to cushion the descent of said lifting frame including a rod rockably mounted on said lifting frame and having a screw threaded portion, a chambered casing rockably mounted on said wheeled supporting means and including a cylinder receiving a portion of said rod, a piston operable within said cylinder and secured to the end of said rod opposite its rockably mounted end, a rotatably mounted ratchet wheel having screw threaded connection with the threaded portion of said rod and disposed within said casing, relative movement between said rod and said casing occasioning rotation of said ratchet wheel, and pawl means also disposed within said casing and cooperating with said ratchet Wheel in locking said lifting frame in elevated position.

17. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, means for raising said frame with respect to said wheeled supporting means, `and means for holding said frame in raised position and cushioning the descent thereof comprising a rod threaded at one end and rockably and nonrotatably mounted at the other end on said lifting frame, a casing enclosing said rod and nonrotatably mounted for rocking movement on said wheeled supporting means, said casing including a cylindrical section adjacent the end which is connected to said wheeled supporting means, a sleeve section carried by said casing on the interior thereof and extending from the opposite end of the casing toward said cylinder, the threaded portion of said rod extending from said cylindrical casing portion into said sleeve portion, a ratchet wheel disposed on said threaded portion of the rod between said sleeve and cylindrical portions of the casing and held thereby against axial movement with. respect tosaid casing, axial movement of said rod with respect to said casing occasioning rotation of said ratchet wheel, a pawl pivotally mounted within said casing adjacent said ratchet wheel and having spring means biasing the same for movement into engagement therewith, an arm carried by said pawl, a shaft journaled for rocking movement in the side of said casing adjacent said pawl arm and having means on the interior of the casing engaging said pawl arm for swinging the vpawl out of engagement with said ratchet wheel, means connected with said shaft exterior of said casing for releasing said pawl, and a piston secured to the end of said rod within the cylindrical portion of said casing and serving in connection therewith as a dashpot for cushioning the descent of said lifting frame.

18. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, a crosshead carried by said wheeled supporting means and having a pair of laterally spaced lugs, a pivot shaft supported on said lugs and extending laterally outwardly therefrom at one side of the truck, means for raising said lifting frame including a lifting arm mounted for rocking movement on said pivot shaft and a link connecting said arm with said frame, means for holding said link in engagement with the lifting frame, a release pedal mounted on said extended end of the pivot shaft for releasing said link to permit the lifting frame to lower, hydraulic means connected between said supporting means and the lifting frame for checking the descent of said frame and including a liquid tight casing, releasable mechanical means disposed within said casing and serving when engaged to positively hold said lifting frame against descent, and means for releasing said mechanical means substantially simultaneously with the release of said link including a shaft extending through a wall of said casing at the same side of the truck as said release pedal, and a link connecting the latter link with said pedal. Y t

19. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, and hydraulic means for checking the descent of said frame and comprising a generally horizontally disposed cylinder and a piston disposed therein having a restricted bore therein communicating with the pressure side of the piston at the upper part of the latter so as to provide for the removal of any entrapped air.

20. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith,' and hydraulic means for checking the descent of said frame and comprising a piston having a ball check valve means therein to provide for rapid elevation of the lifting frame and a member adapted to be secured over said check valve and having an opening disposed in offset relation to said check valve means to hold the ball thereof in position.

2l. In a lift truck, check mechanism comprising a rod fixed against rotation and having a screw threaded portion, a fluid tight casing enclosing said portion of the rod, a rotatably mounted ratchet wheel having screw threaded connection with the threaded portion of said rod and disposed within said casing, relative movement between said rod and said casing occasioning rotation of said ratchet wheel, and pawl means cooperating with said ratchet wheel in locking the latter against rotation in one direction and including a pawl and a pawl spring, both disposed within said casing.

22. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith and having a relatively short ratchet member, and means for raising said frame including a relatively short lifting pawl member engageable with said ratchet member, one of said members having a plurality of teeth and the other having two teeth spaced from each other a distance which corresponds to the distance between a plurality of teeth on said one member, whereby the lifting frame may be raised in a plurality of steps greater in number than the number of teeth on said one member by virtue of the successive engagement between the rst of said two teeth and said plurality of teeth and the subsequent successive engagement between the latter and the other of said two teeth.

23. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, means for raising said frameY including;a liftinglarm movably. mountedon said'Y supporting. means., a. lifting; link connected directly between said` liftingv arm and; saidlifting frame so, as. toexertV a, direct lift:l against the latter, pawl andratchet mechanismcarried by said link and said lifting, frame, a spring pressedmember operatively holding. said link: up inposition with said ratchet means inengagement, wherebyV oscillationsof'said liftingarm4 serve to raise said frame, means for; moving saidA spring pressed member; away fromsaid link. to ,permit the latter tonfall away from said'lifting frame andthereby disengagev said ratchet mechanism, an;arrn.carried by saidllastf named means, means connected `between the lifting. frame and saidwheeledsupportingmeans for'cushioning the descent ofi the latterv andincluding releasable latch means, .and link means connecting the, latter with said arm so that` when the liftinglink; is disengagedthe latch'. means is:A released.

24; A lift truck comprising wheeled supporting means, alifting frame movably` connected therewith, means for: raising saidframe including releasable lifting ratchet means, a. movable member controlling the release` of saidlifting ratchet means, a pedal actuated means controlling the position of, saidy movable member and adapted when moved a certain extent for swinging said movable member to release said lifting ratchet means, said pedal actuated means including a part cooperating with said movable member, when the pedal actuated means has been moved an additional amount, to lock said movable member in released position, an arm on said pedal actuated means, means for holding the lifting frame in elevated position including a releasable locking pawl, a rocking member for releasing the latter, and a link connecting said rocking member with the arm on said pedal actuated means, whereby when the latter locks the lifting ratchet means in released position the locking pawl is held in released position to permit the lifting frame to lower.

25. In a lift truck, a wheeled frame, a lifting platform, a steering head movable on a vertical axis on said frame, a tongue pivoted on a horizontal axis on said head in front of said vertical axis, said tongue having a curved part provided with a curved surface substantially coaxial with the vertical axis when the tongue is in vertical position, a hook having a curved surface, said hook being connected to the platform to lift the same, means constraining the hook to move in a vertical plane which includes said vertical axis, and a link connecting the curved surface of the hook and the curved surface of said part of said tongue, said tongue in moving from a substantially vertical position to a substantially horizontal position moving the hook from a position back of the vertical axis to a position when its curved surface is substantially coaxial with said vertical axis, the throw of said hook and of the said part of the tongue being substantially equal and also being substantially equal to the effective length of said link, whereby a full stroke of said lifting mechanism may be produced by -lowering said tongue within a relatively wide horizontal angle.

26. In a lift truck, a wheeled frame, a lifting platform, a steering head movable on a vertical axis on said frame, a tongue pivoted on the head on a horizontal axis forward of the vertical axis, a member carried by the tongue and having a member disposed substantially coaxially with the vertical axis of the head when the tongue is in substantially vertical position, lifting. mechanism connected to the platform and. comprising "a member, constrained. to.y move toward and away from said vertical; axis in. a vertical longitudinal plane that: includes;l said axis, and link means movably-ccnnecting saidimembers, movement of said; tonguesdownwardly serving to. swing said firstmember away `fromfthe vertiealaxis of said steeringvuheadfa radialdistance great, enough to mover said` second; memberA forward; insaid vertical :pla-ne; to aiposition substantially. coaxial with saidf vertical: axis, whereby; a.k full` stioke of said lifting-mechanism may bey produced. by lowering said; tongue within` ai relatively` wide horizontal angle;

2.7. In alift truck, a wheeled frame, a lifting platform; a steering-head'.` for the frame movableyona vertical axis, a. tongue pivoted on a horizontal axis on thev steering head in front of the ,-verticaljaxis,,andhavinga hook with acurved surfaceioffsetrtozthe rear ofthe. tonguesuch that when, the tonguer is vertical the curved. surface issubstantially,coaxial with said verticalaxis, a second class: lever-V havingv a hooked portion Lwith a.-A curved surface at: its upper end-and pivoted at: itsrlower@ end` on a horizontalaxis on the frame, ai pull rodf connected .to the: intermediate part of the lever, lifting mechanism operable by the pull rod, and a substantially horizontal link connecting the hook on the tongue with the hooked portion on the lever, the throw of the hook by moving the tongue from substantially vertical to substantially horizontal being great enough to swing the lever forward and thereby to move the curved surface of the hooked portion to a position when it is substantially coaxial with the vertical axis of the steering head, whereby a full stroke of said lifting mechanism may be produced by lowering of said tongue within a relatively wide horizontal angle.

28. In a lift truck, supporting means, a steering head therefor movable with respect to said l supporting means about a generally vertical steering axis, a lifting platform movably mounted on said supporting means, means for moving said platform including a member constrained for movement from a position behind said axis to a position in which a portion of said member is in line with said axis, a link pivotally connected at its rear end with said portion of said member and capable of lateral swinging with respect thereto, and means movable with said steering head about said axis for moving said link and including a part pivoted to the forward end of said link for movement laterally of the truck, the axis of lateral swinging between said member and said link coinciding with said steering axis when said member is in its forwardmost position, whereby the same extent of movement in any position of said steering head within a relatively large horizontal angle will shift said member from its position behind said steering axis to a position in which said portion is in line With said steering axis.

" 29. In a lift truck, check mechanism comprising a rod fixed against rotation and having a screw threaded portion, a fluid tight casing enclosing said portion of the rod, a rotatably mounted ratchet wheel having screw threaded connection with the threaded portion of said rod and disposed within said casing, relative movement between said rod and said casing occasioning rotation of said ratchet Wheel, and pawl means disposed within said casing and cooperating with said ratchet wheel in locking the latter y against rotation in one direction.

30. A lift truck comprising wheeled supporting means, a liftingframe movably connected therewith, means for raising said frame including a lifting arm movably mounted on said supporting means, a lifting link connected directly between said lifting arm and said lifting frame so as to exert a direct lift against the latter, pawl and ratchet mechanism carried by said link and said lifting frame, spring biased means reacting against said supporting means for normally holding said link up in position with said ratchet means in engagement, whereby oscillations of said lifting arm serve to raise said frame, and means for moving said spring pressed member away from said link to permit the latter to fall away from said lifting frame and thereby disengage said ratchet mechanism.

31. A lift truck comprising wheeled supporting meansQa lifting frame movably connected therewith, means for raising said frame including re-` tent for swinging said movable member to release said lifting ratchet means, said pedal actuated means including a part engageable with said movable member, when the pedal actuated means has been moved an additional amount, to lock said movable member in released position.

' 32. A lift truck comprising wheeled supporting means, a lifting frame movably connected therewith, means for raising said frame including releasable lifting ratchet parts normally biased for engagement, a movable member for separating said lifting ratchet parts, a pedal actuated means controlling the position of said movable member and adapted when moved a certain extent for swinging said movable member to release said lifting ratchet means, said pedal actuated means including a part engageable with said movable member, when `the pedal actuated means has been moved an additional amount, to lock said movable member in released position, means for holding the' lifting frame in elevated position, and connected with said pedal actuated means for releasing said holding means when said pedal actuated means is moved to lock said movable member in released position..

ARTHUR M. BARRETT. 

